I had the same issue. The number they called me on a business line, no one knows this number. I do not believe it is a debt collector, because first of all I do not think I have collections after me, second because anyone I would owe money to would call my main business line.
Just got one also a couple minutes ago. I was on my business line which is not well known. I saw the number pop up while on call waiting. I have no collections against me either. Must be some solictor. I probably just "won" another contest that I never entered.